According to Yahoo, Facebook is retaliating against the company by claiming violation of ten patents, some of which Yahoo accuses Facebook of purchasing deliberately for the charge.

According to Yahoo, Facebook is retaliating against the company by claiming violation of ten patents, some of which Yahoo accuses Facebook of purchasing deliberately for the charge.

Two months ago, Yahoo filed a lawsuit against Facebook, claiming that the company had violated several of their patents, mostly related to social networking. Earlier this month, Facebook countersued, charging Yahoo of violating some of Facebook’s own patents.

Yahoo points out, however, that eight out of the ten patents that Facebook mentioned were acquired in the last five months. Apparently, none of these eight patents were even developed by Facebook, and some of them even predated the social networking website completely. Thus, Yahoo explains that “any, if not all, of these patents were acquired by Facebook for purposes of retaliation against Yahoo in this case.”

Facebook denies these accusations, and said in a statement that "we remain perplexed by Yahoo's erratic actions. We disagree with these latest claims and we will continue to defend ourselves vigorously."

These battles between both Facebook and Yahoo intersect with a time of great change for both. Yahoo is radically changing the company’s course, having lain off 2,000 employees earlier this month. Meanwhile, Facebook is preparing for an IPO as early as next month, with an anticipated valuation of $100 billion.

Regardless of “whodunit” so far as concerns the patent allegations, Yahoo bemoans that both companies had an agreement to approach each other about intellectual property issues before bringing each other to court. Yet, Yahoo claims that “Facebook provided no notice to Yahoo of any alleged infringement, and Facebook never attempted to resolve any alleged infringement of any of its patents by Yahoo prior to asserting them in litigation.”